Oh there's only 10 levels! I stopped on the last one lol
An undo button would go a long way to improving this game. It's sort of punishing right now having to redo the whole level if you mess up once. Especially with how large the puzzles can be.
Showing the current state of the lights would also be useful to the player because right now you have to mentally keep track of what's turned on and what's turned off. Showing the player gives them a hint as to what still needs to happen.